The present invention relates to the field of the telecommunications networks and more precisely to a telecommunications network having a data-centered structure.
The transmission network evolution leads to data-centered structures wherein services and related infrastructures will evolve and increase their potentialities towards the expectations and needs of the various service operators in a high competitiveness environment, wherein the data transmission and management portion will become more and more significant than the voice-related portion until the current conventional structures will be modified.
In the consolidated network structures the voice and data transport occurs by using synchronous hierarchy networks such as SDH and SONET, in which a series of important additional functionalities are also realized, like those known as OAMandP (Operation, Administration, Maintenance and Protection), as protection, supervision and reconfiguration, so as to provide a complete network management. The transport network layer then interconnects with other layers, such as ATM (Asynchronous Transfer Mode) and IP (Internet Protocol) in a known manner.
This evolution of the networks towards data-centered structures recently has led to the creation of two known types of networks, a first one wherein the quality of service is ensured through the network congestion control, and a second one wherein the quality of service is provided by overprovisioning the network with respect to the whole traffic to be managed.
The first known type of network termed xe2x80x9cIP-over-ATM short-cuttingxe2x80x9d operates in such a way that, once an IP traffic flow has been identified, this is passed from the IP network to the ATM layer, where a possible congestion is best controlled and quality is assured, and then it is transferred over the SDH or SONET layer. The network management function is performed in the ATM and/or SDH or SONET transport layer.
The second known type of network, hereinafter termed network resource overprovisioning, uses high capacity connections forming part of an optical-level transmission layer, to interconnect the IP routers (known interconnection devices between the IP nodes) where all the OAMandP function resides. The transmission capacity is much greater than actually required: by ensuring that optical layer connections between the nodes are overprovisioned and capable of transporting sufficient band, one ensures that the IP network does not become congested.
Said two types of networks have a series of drawbacks which do not allow the problem of congestion to be solved in an effective manner without exceedingly increasing the cost of the network itself.
The first one has the drawback that the more the available bandwidth, the more the traffic increases, hence not allowing the congestion reduction; moreover, it is never easy to ensure that the connections between the routers are large enough to prevent the congestion, and therefore a continuous monitoring of the network congestion level is required to increase the capacity and reduce the queue times.
The second one requires some functionalities such as: traffic detailed management, parameter readjustment like bandwidth reservation, priority level determination, flow control and queue management in a very complicated and expensive manner. Moreover, this model is not applicable to Internet, since the latter is composed of a multiplicity of autonomously developing networks interconnected with each other.
Therefore, the object of the present invention is to overcome all the aforesaid drawbacks and to provide a new telecommunications network architecture, hereinafter referred to as xe2x80x9cIP layer-controlled transmission networkxe2x80x9d, based on an intelligent use of the transport transmission layer serving the IP layer.
In the following, a transmission layer with reference to the present invention is defined by any combination of PDH (Plesiochronous Digital Hierarchy), SDH (Synchronous Digital Hierarchy), SONET, WDM (Wavelength Division Multiplex) or optical network technologies which provides the necessary traffic relations and traffic transport capacities at the lowest cost.
In the IP layer-controlled transmission network in accordance with the present invention, the IP layer controls the transport layer by means of a management interface between the IP layer and the transport one that controls the transport network configuration itself: the IP layer acts as a manager and the transport layer acts as an agent. In the following xe2x80x9cmanagerxe2x80x9d will be called xe2x80x9cclientxe2x80x9d and xe2x80x9cagentxe2x80x9d will be called xe2x80x9cserverxe2x80x9d, according to the Information Technology definitions.
Through the management interface, in case of congestion at some paths, the IP layer requests the transport layer more traffic connections in a manner corresponding to the service request by a customer in a public network or in a virtual private network (VPN). In contrast, in those areas where the problem of the congestion does not exist or is very rare, the IP layer may order the transport layer to release the existing traffic connections, thus determining a general increase in the efficiency and an optimization of the network resource allocation.
The wider the transport network serving the IP layer, the more efficient the resource allocation will be.
To achieve such objects, the present invention provides a telecommunication network as described in claim 1, which forms an integral part of the present description.
The present invention further provides the variants set forth in the dependent claims, which form an integral part of the present description.
The most evident advantages of the new network architecture are the following:
vis-à-vis the first known type of network, xe2x80x9cIP-over-ATM short-cuttingxe2x80x9d, it does not use the ATM layer, thus avoiding the problem of the inefficient ATM cell mapping function, known as xe2x80x9ccell taxxe2x80x9d;
vis-à-vis the second known type of network, network resource overprovisioning, it uses the network and band resources only where necessary, ensuring a higher efficiency level in using the transport layer resources;
in an international Internet network, the national service provider networks (ISP) can use the transport networks of the national service providers to manage the band requests and to control the congestions of the national networks, whilst the international portions of Internet can control the international transport networks to handle their band requests;
the entire congestion control function is made by the IP layer, thus reducing the problem of the Quality of Service (QoS), namely packet loss or round trip delay.